This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A306647 #11 Aug 12 2022 09:18:38 %S A306647 1,6,9,12,14,21,27,30,72,92,96,126,150,162,165,192,225,242,251,261, %T A306647 341,345,384,392,420,455,462,500,540,629,684,704,779,800,825,990,1350, %U A306647 1386,1404,1482,1512,1625,1725,1808,2001,2028,2115,2184,2322,2499,2835 %N A306647 Numbers k such that 2*k^A006530(k) + 1 is prime. %C A306647 All prime members are also in A110932, but the only known example is 251. %H A306647 Mathematics Stack Exchange, <a href="https://math.stackexchange.com/questions/2833659">Are there infinitely many primes of the form 2 m^gpf(m) + 1 when m runs over positive integers?</a> %o A306647 (PARI) print1(1,", ");(gpf(k)=t=factor(k);t[matsize(t)[1],1]);for(k=2,+oo,ispseudoprime(2*k^gpf(k)+1)&&print1(k,", ")) %Y A306647 Cf. A006530, A110932. %K A306647 nonn %O A306647 1,2 %A A306647 _Jeppe Stig Nielsen_, Mar 03 2019